Word recognition is a technique that recognizes words including a plurality of predetermined character strings from information printed on paper. Address recognition is one of application fields of word recognition. Addresses are hierarchized in order of level such as a state, a city, and a place in the city. Thus, the words of each level are recognized by sequentially reading them in the hierarchical order, to thereby recognize a destination address. Assume that, for example, a specific state name contained in information at a first level can be recognized from a plurality of state names. In this case, to specify the name of a certain city, which is information at a subsequent level, it is only necessary to perform recognition among a plurality of city names belonging to the recognized state name. Such a method that limits the words to be recognized in advance is called “word driven recognition”.
Patent Literature 1 discloses a technique relating to a word recognition apparatus that collates a plurality of words with a character string input by a character input device, and recognizes words corresponding to the input character string. The word recognition apparatus disclosed in Patent Literature 1 collates the input character string with the words, and calculates the degree of difference which is a distance between the input character string and each collated word. Further, when words having a similar degree of difference are included in the plurality of words, the word recognition apparatus disclosed in Patent Literature 1 calculates the degree of difference (degree of mutual difference) between the words. Then, the word recognition apparatus disclosed in Patent Literature 1 distinguishes similar words by weighting the degree of mutual difference according to the length of the matched character string. Specifically, assuming that a word length including a larger number of characters among the words to be compared is P′ and the number of characters of a maximum common character string is d12, the degree of mutual difference is weighted using a value calculated by (P′−d12)/P′.
Patent Literature 2 discloses a technique relating to an apparatus that automatically sorts indefinite thin mail pieces or books according to delivery destinations. The apparatus disclosed in Patent Literature 2 is a mail sequencing system that separates objects to be processed one by one, throws the separated objects to be processed, reads information from barcodes or addresses, sorts the objects according to delivery destinations for each of a plurality of sorting bins, and stacks the objects to be processed on a stacking tray provided in each of the sorting bins, thereby performing sorting processing.